1. Field of the Invention
The present invention relates to a substrate processing apparatus and substrate processing method for performing surface processing with a processing liquid such as pure water or a chemical liquid with the use of a table which rotates in a horizontal direction under a state in which a substrate such as a semiconductor wafer or a glass substrate is supported.
2. Description of the Related Art
In a photoresist step as one of semiconductor manufacturing steps, generally, a processing target surface of a semiconductor wafer or a glass substrate (hereinafter, simply referred to as “substrate”) is applied with a resist, and after being exposed in a predetermined pattern, wetted with a chemical liquid to form a resist pattern. After that, in order to remove a dissolved material of the resist together with a developer from the substrate surface, surface processing such as cleaning the substrate surface with pure water and the like is performed.
To give a specific example, in a processing apparatus including a rotatable table, a center of a vertical shaft of the table and a center of a substrate to be subjected to processing are coincident with each other, and under a state in which the substrate is placed horizontally, a processing liquid such as pure water or a chemical liquid is supplied in the vicinity of a center portion of the table, that is, in the vicinity of a center portion of the substrate. Then, the processing liquid is forced to flow by centrifugal force to be spread on the entire processing target surface of the substrate. Thus, the surface processing is proceeded.
However, in such kind of conventional processing apparatus, due to the characteristics of the centrifugal force, the processing liquid moves at higher speed at a peripheral edge portion of the processing target surface of the substrate rotating on the table, and the moving speed of the processing liquid becomes relatively lower toward the center portion. Therefore, depending on the rotating speed of the substrate, the processing liquid stagnates on the processing target surface. Therefore, there are cases where fluctuations are generated in processing effects of the processing target surface and it takes some time to set processing conditions. Hence, there is a problem in that cleaning effects cannot be enhanced.
In view of enhancing the cleaning effects, there is a method disclosed in Japanese Patent Application Laid-open No. 2006-80315. In this method, while rotating the substrate, a cleaning liquid is radially spread from a center portion of the substrate to form a liquid film to clean the substrate, and then under a state in which a dry region is generated in the center portion of the substrate, the substrate is rotated at the number of revolutions of 1,500 rpm or more. At this time, owing to the centrifugal force, a marginal part of the liquid film corresponding to an outer edge of the dry region expands rapidly in the outer peripheral direction of the substrate.
Further, in the apparatus disclosed in Japanese Patent Application Laid-open No. 2007-67080, a position at which the cleaning liquid is supplied from a cleaning liquid nozzle moves from the center portion toward the peripheral edge of the substrate and a gas is blown toward outside of the substrate to a region on the downstream side with respect to the supply position in the rotating direction of the substrate. With this, a dry region in the surface of the substrate expands rapidly outward even if the substrate is rotated at a low rotating speed that does not cause the cleaning liquid to run wildly, and hence it is possible to perform the cleaning processing without stagnation of the liquid flow at the same radial position.
In the method disclosed in Japanese Patent Application Laid-open No. 2006-80315, similarly to the conventional case, there remains a problem that unevenness and the like remain in the vicinity of the center portion of the processing target surface of the substrate. Further, in the apparatus disclosed in Japanese Patent Application Laid-open No. 2007-67080, there remain problems that condition settings for attaining processing uniformity become complex and the like.